Effect of Bioformulation-based Farming Systems on Soil Nutrient Content and Microbial Properties under Okra (Abelmoschus esculentus L.) Cultivation

Okra [Abelmoschus esculentus (L.) Moench] is a globally cherished fruit vegetable known for its fibrous pods, cultivated predominantly in tropical regions during spring, summer and kharif seasons (FAOSTAT, 2021). However, the extensive use of chemical fertilizers in okra cultivation has raised concerns regarding soil degradation, productivity loss and potential food contamination with harmful residues. This situation has spurred a growing demand for sustainable agricultural practices, particularly those utilizing organic inputs.
       
In pursuit of sustainable growth and yield optimization, adequate nutrient provision, including nitrogen (N), potassium (K) and micronutrients, is crucial for okra cultivation. While traditional practices rely heavily on chemical fertilizers, the adverse environmental impacts necessitate alternative strategies. Poultry manure, renowned for its nutrient-rich composition, emerges as a viable organic substitute, enriching soil and promoting crop development (Boateng et al., 2006; Onwu et al., 2014). India, a major contributor to global okra production, is witnessing a shift towards organic inputs and sustainable agricultural practices. With over 546.46 thousand hectares dedicated to okra cultivation and an estimated production of 7158 thousand tonnes in 2022-2023 (Ministry of Agriculture and Farmer’s Welfare, 2024), the need for eco-friendly farming methods is becoming increasingly urgent.
       
Bioformulation fertilizers, as part of smart fertilizer strategies, have shown promise in enhancing nutrient availability and crop production (Karthik and Maheswari, 2020). This study aims to explore the relationship between soil properties, nutrient content, microbial dynamics and okra growth within bioformulation-based farming systems. By investigating the influence of various organic amendments and bioformulations on soil health and plant productivity, we seek to shed light on their effectiveness in promoting sustainable agricultural practices.

The experiment was carried out at the Department of Soil Science and Water Management, College of Forestry, Dr. Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Solan (H.P) during the Kharif seasons of 2020 and 2021. The experiment was laid out in randomized block design with ten treatments and three replications during Kharif seasons 2020 and 2021. The sources of nutrients were vermicompost, poultry manure and organic liquid manures (panchagavya, jeevamrut). The experiment comprised of three replications with a plot size of 1.5 m × 1.5 m.
       
The recommended nutrient doses were applied using a 50:50 ratio of vermicompost and poultry manure based on nitrogen equivalence. These were mixed with soil before seed sowing. Panchagavya (5%) and jeevamrut (5%) organic liquid formulations (Table 1 and 2) were applied twice at 250 ml per plant, as soil drenches, at 15-day intervals starting two weeks after sowing until the third fruit harvest. The experiment comprised 10 treatments: T₁: 100% RDN, T₂-T₄: 90% RDN with panchagavya (5%), jeevamrut (5%) and panchagavya (5%) + jeevamrut (5%) respectively; T₅-T₇: 80% RDN with the same formulations; and T₈-T₁₀: 70% RDN with the same formulations.
 

 

       
The physico-chemical properties of soil were analyzed before as shown in Table 3 and after the experiment, focusing on pH (Jackson, 1973), organic carbon (Walkley and Black, 1934), available nitrogen (Subbiah and Asija, 1956), phosphorus (Olsen et al., 1954), potassium (Merwin and Peech, 1951), copper, iron, zinc and manganese (Lindsay and Norvell, 1978) using standard methods. Soil samples were collected, air-dried, sieved and stored. Microbial properties were assessed through viable microbial count (Subba Rao, 1999) and total microbial biomass (Vance et al., 1987). Enzyme activities viz., dehydrogenase, phosphatase, urease were measured using standard methods given by Casida et al., (1964); Tabatabai and Bremner (1969) and Hoffman (1965) respectivelty. Statistical analysis was performed using ANOVA on a randomized block design with LSD at p≤0.05 significance level.
 

Physico-chemical and nutritional status of soil
 
The aggregated data from Table 4 indicates that none of the tested treatments significantly affected soil pH and EC. The pH values ranged from 6.35 to 6.56 and EC values ranged from 0.17 dS m^-1 to 0.29 dS m^-1. However, the application of various organic manures significantly influenced soil organic carbon levels. The pooled analysis in Table 4 showed that the highest organic carbon content (24.32 g kg^-1) was observed under treatment T₄ [90% RDN + panchgavya @ 5% + jeevamrut @ 5%], while the lowest (20.58 g kg^-1) was recorded in treatment T₉ [70% RDN + jeevamrut @ 5%]. The observed increase in soil organic carbon is consistent with the findings of Bhadhulkar et al., (2000) and Selvi et al., (2004), who reported long-term application of FYM enhancing soil properties. Similarly, bioformulation fertilizers have been noted to improve nutrient availability and microbial biomass, thereby supporting sustainable agricultural practices (Kumar and Brar, 2021).
 

 

 
Available macronutrients
 
Table 5 shows a significant rise in soil nitrogen content after applying various organic amendments. Treatment T₄ [90% RDN + panchgavya @ 5% + jeevamrut @ 5%] displayed the highest nitrogen value (418.0 kg ha^-1), a 26% increase over the control [T₁ (100% RDN)], as shown in Fig 1. This increase is attributed to nutrient-rich organic manures like vermicompost and poultry manure, as noted by Ullah et al., (2008). Likewise, T₄ exhibited a notable increase in available phosphorus content, reaching 78.22 kg ha^-1, a 30% rise compared to the control, consistent with findings by Ray et al., (2005) and Sharma et al., (2008). Furthermore, T₄ showed a significant elevation in available potassium content, recording 423.7 kg ha^-1, a 22.03% increase over the control, supported by research conducted by Aziz et al., (2010). Roy and Kashem (2014) also support these findings, emphasizing the effectiveness of organic manures like cow dung and chicken manure in improving soil nutrient status. Across both experimental years, T₄ consistently enriched soil nutrients, highlighting the effectiveness of bioformulation-based farming systems in enhancing soil fertility and promoting optimal crop growth.
 

 
DPTA extractable cations
 
Table 6’s pooled analysis emphasizes the significant influence of various organic manures on soil DPTA extractable cations. Furthermore, the examination of available micronutrient cations in Table 6 reveals notable differences due to organic manure application. Particularly, treatment T₄ [90% RDN + panchgavya @ 5% + jeevamrut @ 5%] displays the highest levels of available micronutrient cations, including Cu, Fe, Zn and Mn, at 4.62 mg kg^-1, 19.87 mg kg^-1, 3.00 mg kg^-1 and 12.82 mg kg^-1, respectively. These values indicate a substantial increase compared to the control treatment [T₁ (100% RDN)]. This enhancement aligns with previous studies by Beckman (1973) and Udah et al., (2005), which reported positive effects of organic manure usage on soil micronutrient levels. Additionally, Reddy and Reddy (1999) support these findings, highlighting the role of organic manures in boosting available soil micronutrients. Overall, the results suggest that organic manure application, especially treatment T₄, significantly boosts micronutrient cation availability compared to the control, consistent with previous research emphasizing the positive impact of organic manure on soil micronutrient levels.
 

 
Soil microbial properties
 
Microbial count
 
Table 7 illustrates the impact of organic amendments on soil microbial populations. Treatment T₄ [90% RDN + panchgavya @ 5% + jeevamrut @ 5%] recorded the highest bacterial count (203.34 × 10⁸ cfu g^-1 soil), while T₁ [100% RDN] had the lowest (142.2 × 10⁸ cfu g^-1 soil). Similarly, T₄ showed the highest fungal count (4.29 × 10³ cfu g^-1 soil) and the highest actinomycetes count (3.69 × 10² cfu g^-1 soil), with T₁ having the lowest counts (3.19 × 10³ cfu g^-1 soil for fungi and 2.61 × 10² cfu g^-1 soil for actinomycetes). These results align with previous research (Jain et al., 2014).
 

 
Microbial biomass
 
Table 8 shows that microbial biomass-C was highest in T₄ (65.02 µg g^-1 soil) and lowest in T₁ (46.13 µg g^-1 soil). Treatment T₄ showcased the highest microbial biomass-C, contrasting with T₁ displaying the lowest. This aligns with findings by Dou et al., (2023), highlighting increased microbial biomass in organic tomato farming systems with organic inputs and straw mulching. The observed enhancements emphasize the positive repercussions of organic farming practices on soil microbial activity.
 

 
Soil enzymes
 
Table 9 illustrates the significant impact of different treatments on soil dehydrogenase activity over both study years. T₄ [90% RDN + panchgavya @ 5% + jeevamrut @ 5%] showed the highest dehydrogenase activity (4.80 mg TPF h^-1 g^-1 soil), followed by T₇ (4.30 mg TPF h^-1 g^-1 soil), while T₁ exhibited the lowest activity (2.91 mg TPF h^-1 g^-1 soil). Additionally, phosphatase activity was notably influenced by various organic amendments across both years, with T₄ displaying the highest activity (30.98 µmole PNP h^-1 g^-1 soil) and T₁ the lowest (19.21 µmole PNP h^-1 g^-1 soil), consistent with Krishnakumar et al., (2005), who observed increased phosphatase activity with FYM application. Furthermore, urease enzyme activity varied among treatments, with T₄ showing the highest activity (0.29 mg NH⁺ g^-1 soil) and T₁ the lowest (0.16 mg NH⁺ g^-1 soil). These results emphasize the significant impact of different treatments on soil enzyme activity, with T₄ displaying the highest dehydrogenase and phosphatase activities and T₁ showing the lowest. Similarly, T₄ exhibited the highest urease activity, while T₁ had the lowest, aligning with Chandrakala (2008), indicating increased enzyme activity with organic input application, such as FYM. Kashyap and Khokhar (2017) further support these results, linking improved urease activity to FYM application and enhanced crop productivity. Overall, these findings underscore the positive influence of organic farming practices on soil microbial properties and enzyme activity, promoting soil health and fertility. They highlight the significance of sustainable agricultural practices aimed at fostering soil biological activity to sustain long-term agricultural productivity.
 

The thorough evaluation of soil characteristics and nutrients after applying organic amendments offers vital insights into sustainable farming. While minimal impact is seen on pH and EC, organic manure notably boosts soil organic carbon, indicating enhanced fertility and carbon storage potential. Treatment T₄ consistently proves most effective in enriching soil properties and microbial activity. This highlights the importance of bio-based farming, like Panchgavya and Jeevamrut, for soil health and crop yield. The importance of bioformulation-based farming systems, such as Panchagavya and Jeevamrut, in promoting soil health and crop yield has been increasingly recognized. Smart fertilizer strategies incorporating bioformulation fertilizers offer a viable path towards sustainable agriculture. Future research should focus on the lasting effects of organic manure, with longitudinal studies across multiple crop cycles. Exploring interactions with practices like crop rotation and cover cropping could optimize productivity and reduce environmental harm. A multidisciplinary approach merging soil science, agronomy, microbiology and agroecology is essential for tackling agricultural challenges sustainably, ensuring resilient and productive farming systems while safeguarding the environment.

Conceptualization and designing of research work (F. Lalkhumliana, Rajesh Kaushal); Execution of field/lab experiments and data collection (F. Lalkhumliana); Analysis of data and interpretation (F. Lalkhumliana, S. Ananthakrishnan); Preparation of manuscript (F. Lalkhumliana, S. Ananthakrishnan).

All authors declare that they have no conflict of interest.